class TTY::Prompt::Paginator

Constants

DEFAULT_PAGE_SIZE

Public Class Methods

new(options = {}) click to toggle source

Create a Paginator

@api private

# File lib/tty/prompt/paginator.rb, line 11
def initialize(options = {})
  @last_index  = Array(options[:default]).flatten.first || 0
  @per_page    = options[:per_page]
  @lower_index = Array(options[:default]).flatten.first
end

Public Instance Methods

max_index() click to toggle source

Maximum index for current pagination

@return [Integer]

@api public

# File lib/tty/prompt/paginator.rb, line 22
def max_index
  raise ArgumentError, 'no max index' unless @per_page
  @lower_index + @per_page - 1
end
paginate(list, active, per_page = nil, &block) click to toggle source

Paginate collection given an active index

@param [Array] list

a collection of choice items

@param [Integer] active

current choice active index

@param [Integer] per_page

number of choice items per page

@return [Enumerable]

@api public

# File lib/tty/prompt/paginator.rb, line 39
def paginate(list, active, per_page = nil, &block)
  current_index = active - 1
  default_size = (list.size <= DEFAULT_PAGE_SIZE ? list.size : DEFAULT_PAGE_SIZE)
  @per_page = @per_page || per_page || default_size
  @lower_index ||= current_index
  @upper_index ||= max_index

  # Don't paginate short lists
  if list.size <= @per_page
    @lower_index = 0
    @upper_index = list.size - 1
    if block
      return list.each_with_index(&block)
    else
      return list.each_with_index.to_enum
    end
  end

  if current_index > @last_index # going up
    if current_index > @upper_index && current_index < list.size - 1
      @lower_index += 1
    end
  elsif current_index < @last_index # going down
    if current_index < @lower_index && current_index > 0
      @lower_index -= 1
    end
  end

  # Cycle list
  if current_index.zero?
    @lower_index = 0
  elsif current_index == list.size - 1
    @lower_index = list.size - 1 - (@per_page - 1)
  end

  @upper_index = @lower_index + (@per_page - 1)
  @last_index = current_index

  sliced_list = list[@lower_index..@upper_index]
  indices = (@lower_index..@upper_index)

  return sliced_list.zip(indices).to_enum unless block_given?

  sliced_list.each_with_index do |item, index|
    block[item, @lower_index + index]
  end
end